•In the AlCoCrCuFeNi High-Entropy Alloy, copper was replaced by titanium for hardening effects.•Samples were synthesized following a solid-state route (mechanical alloying and vacuum sintering).•Hardness and elastic modulus were determined using nanoindentation testing.•Evidence shows a clear correlation between composition/crystalline structure and final mechanical properties.•Prepared samples were composed of three main phases and nanometric precipitates. The concept of High-Entropy Alloy (HEA) expanded the research field of advanced metallic materials for various applications, like the development of ultra-hardness ballistic protection materials for national security. Although there can be hundreds of compositions, carefully selecting the constituent is mandatory to improve their mechanical behavior, keeping in mind their microstructural array based on chemical composition. In the present study, the AlCoCrCuFeNi HEA was modified, replacing copper with titanium, looking for the formation of a Ti-rich BCC phase for hardening effects. Samples were prepared following the powder metallurgy route, including mechanical alloying favoring the generation of a nanocrystalline microstructure. Studies based on structure, microstructure and nanoindentation testing on each phase of the alloy were performed to determine the correlation between their composition, crystalline structure and mechanical properties. Evidence showed the formation of three main micrometric phases (two BCC and one tetragonal) coexisting with a nanometric dispersion of rounded precipitates. Nanoindentation testing shows that the main hardening effect was related to the tetragonal phase formation by a solid-solution strengthening mechanism. This phase reached the highest hardness (14.9 GPa); meanwhile, the richest Ti phase showed the lowest elastic modulus, titanium favors the material ductility.